As a brand new 'Game of Thrones' series readies to air this August, we're still intrigued as to why another spin-off failed to make it past the pilot stage.

But we may finally have that answer. When it was announced that the 'GOT' spin-off 'Bloodmoon' had been cancelled, it did come as a bit of a blow to fans of the series, purely because it sounded kind of cool.

Naomi Watts and Jamie Campbell Bower were just two of the stars who were set to lead the prequel series, which was set to tell the untold story of when the White Walkers first set up shop in Westeros, 10,000 years before the events in the original HBO series.

Originally called 'The Long Night', the pilot episode alone is believed to have set back HBO somewhere in the region of $30/35 million. Principal photography took place in Northern Ireland.

Speaking to The Hollywood Reporter this week ahead of the first official 'Game of Thrones' spin-off to get the greenlight, 'House of the Dragon', were some of the HBO bosses.

First, the creator of the franchise on which the series is based, George R. R. Martin, admitted to having doubts: "'Bloodmoon' was a very difficult assignment. We’re dealing with a much more primitive people. There were no dragons yet. A lot of the pilot revolved around a wedding of a Southern house to a Northern house and it got into the whole history of the White Walkers."

Martin had only published about eight sentences about the time period, and when he made his worries apparent to HBO, one insider said: "Having a show that’s pure invention and had George scratching his head at various moments was troubling at times."

HBO chief content officer, Casey Bloys opened up as to why 'Bloodmoon' was cancelled: "It required a lot more invention; it was higher risk, higher reward. There wasn’t anything glaringly wrong with it. Development and pilots are hard."

Robert Greenblatt, who was the chairman of HBO’s parent company WarnerMedia at the time added: "It wasn’t unwatchable or horrible or anything. It was very well produced and looked extraordinary. But it didn’t take me to the same place as the original series. It didn’t have that depth and richness that the original series’ pilot did."

According to the news piece, George R. R. Martin has never been allowed to see the pilot. Which, weirdly, makes us want to see this pilot even more.

'House of the Dragon' begins on Sky Atlantic and NOW on August 22.